Copigmentation effect of phenolic compounds on red currant juice anthocyanins during storage

Copigmentation has been suggested as a main colour stabilising mechanism in plants protecting the coloured flavylium cation from the nucleophilic attack by the water molecule. In this study influence of phenolic compounds addition (catechol, 4-methyl catechol, (+)-catechin and gallic acid) on stability of red currant juice anthocyanins (copigment:pigment molar ratio 50:1 and 100:1) during 30 days of storage at 4 °C was investigated. Stability of anthocyanins was evaluated through determination of anthocyanins, total colour difference (ΔE*), kinetic parameters and anthocyanin retention. The initial anthocyanin content of red currant juice was 44.34 mg/100 g. During storage degradation of anthocyanins occurred. After storage anthocyanin content of red currant juice was 38.87 mg/100 mL. However, in samples with addition of phenolic compounds degradation was less pronounced due to formation of pigment-copigment complex (i.e. copigmentation). Anthocyanin content in samples with addition of phenolic compounds ranged from 39.2 to 43.83 mg/100 mL, depending on phenolic compound, its concentration and storage time. The lowest degradation was observed when gallic acid was added. Monitoring only λmax of absorption spectrum of juices, one can get incomplete picture of colour stability of red currant juice. It was important to monitor total colour change (ΔE*) with CIELAB colour system since all parameters are taken into account. The lowest ΔE*, after 30 days of storage, had samples with addition of catechol and (+)-catechin (0.83 and 0.86, respectively), while the highest values had samples with addition of gallic acid (1.26)

Influence of different extracts addition on total phenols, anthocyanin content and antioxidant activity of blackberry juice during storage

The aim of this study was investigation of influence of different extracts addition on total phenols, anthocyanin content, antioxidant activity and percent of polymeric colour of blackberry juice during storage of 52 days at 4 °C. Anthocyanin content of control sample (blackberry juice without extracts addition) was 149.91 mg/L. Samples with addition of extracts (olive leaf, pine bark PE 5:1, pine bark PE 95 %, green tea, red wine PE 30 %, red wine PE 4:1 and bioflavonoids had higher anthocyanin content (from 152.42 to 161.19 mg/L) in comparison to control sample. Sample with addition of bioflavonoids had the highest anthocyanin content. Samples with addition of extracts had much higher total phenol content and antioxidant activity than control sample, what was expected since extracts are rich in phenols. During storage decrease of phenols, anthocyanins and antioxidant activity occurred in higher or lesser extent, depending on extract type addition. Anthocyanin content in control sample was 119.85 mg/L. Samples with addition of bioflavonoids, olive leaf, pine bark PE 5:1 and red wine PE 4:1 had lower (from 103.44 to 118.84 mg/L), while other samples had higher (from 131.99 to 135.57 mg/L) anthocyanin content than control sample. After storage, decrease of anthocyanins was followed with increase of percent of polymeric colour, with exception of samples with addition of green tea

Prevention of thermal degradation of red currant juice anthocyanins by phenolic compounds addition

The aim of this study was investigation of prevention of thermal degradation of the red currant juice anthocyanins by addition of different phenolic compounds (catechol, 4-methyl catechol, catechin, chlorogenic acid and gallic acid). Phenolic compounds were added in 50:1 and 100:1 copigment:pigment molar ratio. Red currant juice samples were heated at 30, 50, 70 and 90 °C for 1 hour. Thermal degradation of anthocyanins was investigated through determination of anthocyanin content and calculation of the reaction rate constant, half-life of degradation, activation energy and anthocyanin retention. Anthocyanin content ranged from 34.32 mg/100 mL to 47.97 mg/100 mL in a red currant juice, depending on temperature. When phenolic compounds were added anthocyanin content ranged from 34.94 mg/100 mL to 50.41 mg/100 mL, depending on both temperature and added phenolic compounds. In all cases when phenolic compound were added, anthocyanin content, half-lives of degradation increased and the reaction rate constants decreased. The thermal degradation of anthocyanins was lower when phenolic compounds were added due to copigmentation effect. With increase of temperature copigmentation effect was less pronounced. The most contributing phenolic compounds on anthocyanin stability at 30 °C was gallic acid, at 50 °C and 70 °C catechin, and at 90 °C 4-methyl catechol. Concentration of phenolic compounds also had influence on investigated parameters

Total phenol content and antioxidant activity of water solutions of plant extracts

Water solutions of extracts were investigated for total phenol content, flavonoid content and antioxidant activity. Susceptibility to degradation of water solutions of plant extracts, under light and in the dark, during storage at room temperature was investigated in order to determine their stability prior to their application for fortification of food products. Large dispersion of total phenol (TP) content in the investigated model solutions of selected extracts (olive leaves, green tea, red grape, red wine, pine bark PE 5:1, pine bark PE 95 %, resveratrol), ranging from 11.10 mg GAE/100 mL to 92.19 mg GAE/100 mL was observed. Consequently, large dispersion of total flavonoids (TF) content (8.89 mg to 61.75 mg CTE/100 mL) was also observed. Since phenols have been mostly responsible for antioxidant activity of extracts, in most cases, antioxidant activity followed the TP content. That was proven by estimation of correlation coefficient between the total phenol content and antioxidant activity. Correlation coefficients between investigated parameters ranged from 0.5749 to 0.9604. During storage of 5 weeks at room temperature loss of phenols and flavonoids occurred. Antioxidant activity decreased with the decrease of TP and TF content. Degradations of phenols and flavonoids were more pronounced in samples stored at light

MICROENCAPSULATION OF GLUCOSYL-HESPERIDIN IN ALGINATE/CHITOSAN HYDROGEL BEADS

Glucosyl-hesperidin is a water soluble derivate of hesperidin. Both these derivates have many health-promoting properties such as antioxidant, anti-inflammatory and antimicrobial activities. However, the low water solubility of hesperidin disables its wide utilization in the food and pharmaceutical industries so glucosyl-hesperidin has an advantage concerning new product development. The aim of the study was to produce hydrogel beads filled with glucosyl-hesperidin by applying microencapsulation technique using vibration technology. Beads were fabricated under the same operating conditions of the encapsulator and obtained by dropping a mixture of glucosyl-hesperidin and alginate into different hardening solutions (calcium chloride or calcium chloride-chitosan) with different times of complexation (30 min or 90 min). The highest retention ability of glucosyl-hesperidin had chitosan-alginate beads, which were complexed for 30 min (590.93 mg/kg), while the lowest retention ability was observed for alginate beads with a complexation time of 30 min (409.94 mg/kg). Beads were stored for 7 days at ambient temperature and in the presence of light. The highest amount of glucosyl-hesperidin was detected in chitosan-alginate beads as after preparation. Results of this study give insight into glucosyl-hesperidin encapsulation into hydrogel beads and its behavior during storage

MICROENCAPSULATION OF GLUCOSYL-HESPERIDIN IN ALGINATE/CHITOSAN HYDROGEL BEADS

Glucosyl-hesperidin is a water soluble derivate of hesperidin. Both these derivates have many health-promoting properties such as antioxidant, anti-inflammatory and antimicrobial activities. However, the low water solubility of hesperidin disables its wide utilization in the food and pharmaceutical industries so glucosyl-hesperidin has an advantage concerning new product development. The aim of the study was to produce hydrogel beads filled with glucosyl-hesperidin by applying microencapsulation technique using vibration technology. Beads were fabricated under the same operating conditions of the encapsulator and obtained by dropping a mixture of glucosyl-hesperidin and alginate into different hardening solutions (calcium chloride or calcium chloride-chitosan) with different times of complexation (30 min or 90 min). The highest retention ability of glucosyl-hesperidin had chitosan-alginate beads, which were complexed for 30 min (590.93 mg/kg), while the lowest retention ability was observed for alginate beads with a complexation time of 30 min (409.94 mg/kg). Beads were stored for 7 days at ambient temperature and in the presence of light. The highest amount of glucosyl-hesperidin was detected in chitosan-alginate beads as after preparation. Results of this study give insight into glucosyl-hesperidin encapsulation into hydrogel beads and its behavior during storage

THE CONTENT OF POLYPHENOLS, ANTHOCYANINS AND ANTIOXIDANT ACTIVITY OF FRUIT TEA

U ovom radu ispitivan je utjecaj vremena i temperature maceracije tijekom pripreme voćnih čajeva (brusnica, borovnica, trešnja i šumsko voće) na sadržaj polifenola, antocijana, flavonoida, kondenziranih tanina i antioksidativnu aktivnost. Čajevi su macerirani pri 80 i 100 °C 5 donosno 8 minuta. Ispitivan je i utjecaj ponovljene maceracije istih čajeva na sadržaj navedenih komponenti. Maceracijom čajeva pri 100 °C, u uzorcima je određen veći sadržaj polifenola, antocijana, flavonoida i kondenziranih tanina, a vrijednosti antioksidativne aktivnosti su bile veće. Nakon ponovljene maceracije sadržaj polifenola, flavonoida i kondenziranih tanina bio je znatno manji. Vrijednosti antioksidativne aktivnosti su također bile niže nakon ponovljene maceracije.In this work, influence of time and temperature of maceration of fruit tea (cranberry, blueberry, cherry and wild fruit) on content of phenols, anthocyanins, flavonoides, condensed tannins and antioxidant activity was investigated. Maceration temperatures were 80 and 100 °C and maceration time 5 and 8 minutes. Also, influence of repeated maceration of same samples on mentioned parameters was investigated. All samples macerated at 100 °C had the highest content of phenols, anthocyanins, flavonoides, condensed tannins and antioxidant activity. After repeated maceration content of mentioned compounds and values of antioxidant activity were lower

GLUCOSINOLATES: BIOAVAILABILITY AND INFLUENCE ON HUMAN HEALTH

Glukozinolati su jedinstvena i važna skupina sekundarnih metabolita u nekim vrstama biljaka. Ubrajaju se u specifičnu skupinu kemijskih spojeva tzv. \u27fitokemikalija\u27 koja je zastupljena u 16 botaničkih porodica reda Capparales. Za prehranu ljudi najznačajnija je porodica Brassicaceae u koju se ubrajaju kupus, brokula, cvjetača, prokulice, roktvica, repa, gorušica. U ovom radu obuhvatiti će se svi parametri koji vladaju u različitim stadijima od uzgoja do prerade povrća iz porodice Brassicaceae, na biodostupnost glukozinolata i njihovih razgradnih produkata, i na zdravlje ljudi. Glukozinolati su kemijski stabilni sve dok ne dođu u kontakt s enzimom mirozinazom (β-tioglukozid glukohidrolaza; EC 3.2.1.147). Hidroliziraju se u niz biološki aktivnih tvari (izoticijanati, indol-3-karbinol). Osim što se konzumira svježe, povrće se vrlo često procesira, te ovisno o uvjetima prerade, prisutni glukozinolati se mogu razgraditi što može imati za posljedicu promjenu njihove biološke aktivnosti. Mnogobrojna epidemiološka istraživanja dokazala su i potvrdila pozitivan učinak konzumiranja povrća iz porodice Brassicaceae, a time i unosa glukozinolata u ljudski organizam. U radu će biti obrađen mehanizam njihovog pozitivnog djelovanja (antifungalno, antibakterijsko, antioksidativno, antimutageno, antikancerogeno djelovanje). Osim što imaju pozitivan učinak u ljudskom organizmu, glukozinolati i njihovi razgradni produkti mogu imati i antinutritivni učinak, što je također potrebno uzeti u obzir, međutim, potrebno je provesti još istraživanja u tom smjeru.Glucosinolates are unique group of secondary plant metabolites. They are specific chemical compounds i.e. phytochemicals occurring in about 16 botanical families of the order Capparales. For the human diet, the most important are representatives of the Brassicaceae like cabbage, Brussels sprouts, broccoli, cauliflower, radish, mustard. In this review, we will elaborate all the relevant steps in the food supply chain of Brassica vegetables and their influence on intake and bioavailability of glucosinolates and bioactive breakdown products in relation to human health. Plants possessing glucosinolates also contain an enzyme, myrosinase (β-thioglucoside glucohydrolase; EC 3.2.3.1). When glucosinolates and myrosinase come in contact with each other in the presence of water, the enzyme immediately causes the hydrolysis of the glucosinolates. Those breakdown products of glucosinolates are also biologically active. Except consuming fresh, vegetables are often processed. Depending on conditions during processing, degradation of glucosinolates can occur resulting in change of their bioavailability and biological activity. Numerous epidemiological studies have proven positive influence of consumption of Brassica vegetables on human health. Glucosinolates and their enzymatic hydrolysis products have the potentially beneficial activities as antioxidants, antifungal, antibacterial, bioherbicidal, biopesticidal, antimutagenic and anticarcinogenic agents. Next to their positive effect on human health, the antinutritional effects and the possible toxicity of glucosinolates were also observed. Those effects should also be taken in account and there is a need for further investigation of these effects

Effect of galactomannan hydrocolloids on gelatinization and retrogradation of tapioca and corn starch

The aim of the present study was to investigate the effect of galactomannan hydrocolloids (guar gum and locust bean gum) on gelatinization and retrogradation of tapioca and corn starch. Differential scanning calorimetry (DSC) was used to characterize the behaviour of tapioca and corn starch with and without additives. Results showed that guar gum and locust bean gum retarded the retrogradation of tapioca and corn starch at both investigated temperatures (4 and 25 °C). Guar gum retarded retrogradation of tapioca starch more than locust bean gum, on the other hand, locust bean gum had a greater effect on reduction of the recrystallization of corn starch. Temperatures of gelatinization did not vary significantly in starch-hydrocolloid systems. Additions of galactomannan hydrocolloids caused a decrease in gelatinization enthalpy of both starches

APPLICATION OF Litsea cubeba TO IMPROVE SHELF-LIFE OF FRESH-CUT ‘PACKHAM’S TRIUMPH’ PEARS

Plant-derived natural products can be of interest as a source of alternatives to improve the shelf-life and the safety of food. Litsea cubeba has recently received much attention due to multiple functions as antibacterial, antifungal, insecticidal, antioxidant and anticancer agent. The application of Litsea cubeba essential oil (LC) in this investigation is one of the first experiments made in order to improve shelf-life of minimally processed fruits. The aim of this work was to investigate the effect of LC at different concentrations (50, 100 and 250 ppm), on shelf-life of fresh-cut pears ‘Packham’s Triumph’ variety. Colour of fresh-cut pears as well as, polyphenol content, antioxidant activity and flesh firmness of untreated and treated samples, were determined. Analysis were carried out immediately following oil treatments, and on 1, 7, 14 day of storage at 2 °C. Treatment with 50 ppm of LC was the most effective treatment to maintain colour of fresh-cut pears during 14 day of storage. Phenolic compounds and antioxidant activity in samples treated with solutions of LC remain stable during 14 day of storage. The lowest loss of firmness was detected in fresh-pears treated with 250 ppm LC. Essential oil of Litsea cubeba has promising application as a treatment of fresh-cut pears